The invention relates generally to refractory materials and, more particularly, to refractory materials with reduced slag penetration.
Coal and other hydrocarbons may be subjected to partial combustion to produce gases that are useful as fuels and starting materials for chemical syntheses. This gasification typically takes place in large furnaces that allow the hydrocarbon feedstock to be subjected to high temperatures to produce the gaseous products of the reaction. In addition to the desired products, the by-products of the reaction may include waste products, such as slag. Slag is a low viscosity blend of inorganic oxides that is produced as a by-product in a slagging coal gasifier when the coal or coke is partially oxidized. The slag may, for example, contain silica, aluminum oxide, calcium oxide and iron oxide.
To contain the heat of the reaction, the walls of the gasifier may be lined with a refractory material that is able to withstand high temperatures. Typically, the refractory material is quite porous. For example, common refractory materials are sintered bricks with highly connected pore structures. These materials are vulnerable to damage by the gasification reaction. As the slag byproduct flows along the walls of the gasifier, it infiltrates into the pores in the refractory material. This infiltration may cause degradation of the refractory material through dissolution and/or cracking.
As a result of slag infiltration, refractory material that lines a gasifier may break down relatively quickly and may need to be replaced several times during the lifespan of the gasifier. The refractory material may be replaced by manual workers entering the gasifier and removing the damaged bricks or, in certain cases, the entire lining. Because the gasifiers are operated at very high temperatures, this may involve shutting the gasifier down and allowing it to cool for several days until workers can safely enter. Such replacement of the refractory material is generally costly, both in terms of the materials and labor involved and operating time lost, because the gasifier cannot run for several days during the replacement process.